A typical adsorption heat pump includes an adsorber that adsorbs and desorbs a coolant, such as water, by using an adsorbent, an evaporator that generates cooling energy by evaporating the coolant as the adsorber performs an adsorbing operation, and a condenser that condenses the vapor of the coolant desorbed and adsorbed at the adsorber and supplies the condensed coolant to the evaporator. The adsorber, the evaporator, and the condenser are arranged in series along a coolant circulation pipe.
Examples of hot water used in the adsorber when desorbing the coolant from the adsorbent include vehicle-engine cooling water at 85° C. to 90° C., hot discharge water at 60° C. to 80° C. from a high-molecular fuel cell, and hot discharge water at 60° C. to 80° C. from a cogeneration device.
On the other hand, examples of cooling water used in the adsorber when adsorbing the coolant to the adsorbent include cooling water at 30° C. to 40° C. used in a radiator of a vehicle and cooling water or river water at 25° C. to 35° C. used in a building.
Thus, by selecting an adsorbent with high coolant adsorption characteristics within a temperature range and at a vapor pressure within the adsorber, which are related to the operation of the adsorption heat pump, it is expected that the performance of the adsorption heat pump can be improved.
Japanese Laid-open Patent Publication No. 2005-205331 discusses an adsorption heat pump containing an adsorbent that exhibits high coolant adsorption efficiency even when there is a small temperature difference between the hot water and the cooling water used in the adsorber.
Japanese Laid-open Patent Publication No. 2009-180405 discusses an adsorption heat pump equipped with a plurality of adsorbers that are arranged in parallel along a coolant circulation pipe. The adsorbers contain adsorbents with which the adsorbers perform coolant desorption effectively in different temperature ranges and different vapor pressure ranges. This adsorption heat pump has a function of selecting one of the adsorbers in accordance with an operational temperature range of the adsorption heat pump.
In each adsorber of the adsorption heat pump, the temperature of the hot water or cooling water flowing through a pipe extending through the adsorber varies between near the inlet of the pipe and near the outlet of the pipe. This is because the hot water is gradually cooled and the cooling water is gradually heated by the adsorbent.
This sometimes makes it difficult to maintain high adsorption characteristics in a part of the adsorbent in the adsorber. In that case, it is assumed that there is a difficulty in achieving the original coolant adsorption efficiency of the adsorber in accordance with the adsorbent.